How does a technician voice a piano?

Before you or your technician can fully evaluate then tone of your piano, it must be well-tuned. Tuning is the first step in improving the sound of any piano and may actually provide the tone you desire. If the tone is still not satisfactory. Your technician will inspect the action, hammers and strings. If these components are severely worn, major repairs may be required before an improved tone is possible.

  • Moderately worn hammers can be re-shaped with sandpaper to remove string grooves and restore their original rounded shape. Next, the hammers are aligned to strike each string squarely.
  • Action regulation should be checked or adjusted. This ensures an even, powerful response from each key.
  • If tuning, hammer shaping and regulation are correct, the tone probably will be balanced but still may be too bright or mellow for your taste. If so, your technician might recommend voicing the hammers.
  • For a tone that is too loud, too bright or seems to die out too quickly, softening the hammers felt often is recommended. This is usually done by inserting needles into specific areas of the hammer to increase flexibility.
  • For a tone that is too weak or too mellow, hardening of the hammer felt may be necessary. This is usually done by filing away soft outer layers of hammer felt or by applying a chemical hardening solution.
  • Once the overall tone is correct, individual notes are voiced to make the tone as even as possible from one end of the keyboard to the other. In some pianos certain notes still may sound different from their neighbors, no matter how skillfully the technician voiced the piano. This most commonly occurs about an octave below middle C, where the strings change from steel wires wrapped with copper to plain steel. Such irregularities are a result of design compromises, and usually cannot be corrected by voicing. 

The preceding article is a reprint of a Technical Bulletin published by the Piano Technicians Guild, Inc.It is provided on the Internet as a service to piano owners.